Forbears to kill with spears (6)
I believe the answer is:
spares
'forbears' is the definition.
Although both the answer and definition are verbs in their -s form, I don't see how one could define the other.
'kill with spears' is the wordplay.
'spears' anagrams to 'SPARES'.
But, I am not sure how this is indicated.
'to' is the link.
Can you help me to learn more?
(Other definitions for spares that I've seen before include "Extras in case of necessity" , "Is merciful towards, refrains from hurting" , "Replacement items, like tyres" , "Extras with spears" , "Lets off; reserve parts" .)